RE: How do you get in shape.
Kinda related to my specialty (physiology). I have also presented several lectures on altitude related illness.
1. Start soon, don't wait. Start now. See a doc before starting any exercise program.
2. I think the first issue is to increase cardiac and respiratory efficiency. This will help eliminate minor symptoms of altitude sickness. It will also increase your level of fun by: helping to give a steadier hold on your weapon and help you get where you wanna go with less effort.
Aerobic training is the best way. Not the only, but the best. Start by determining your target heart rate. Take 220 and subtract your age. For example, lets use that 20 year old nephew. 220-20 = 200. 200 is your theoretical maximum heart rate. Take 85% of that max (.85X200=170) to get your upper limit of 170. Take 65% of that number (200X.65= 130) to get your lower limt of 130. In other words for a 20 year old his/her target heart rate should be between 170 and 130 beats per minute. If you keep your hear rate within that range for about 30-45 minutes, 3-4 sessions per week you will increase your cardiac and respiratory efficiency.
2. Unless you have a strong nephew or two to help lift that bull, you should also consider including some strength training as well. Too much info to post details here. Look for a good gym. Ask the managers if their folks are certified by ACSM (American College of Sports Medicine) and/or NSCA (National Strength and Conditioning Association). If they are not, keep looking until you find a gym who does have such certified instructors. Weight training will increase the efficiency of your heart as much as a similar level of aerobic training. Weight training places a pressure overload on the heart; aerobic training places a volume overload on the heart....both will increase cardiac efficiency. But, aerobics is a much better method for increasing respiratory efficiency. There is some theory which suggests that folks who lift a lot with their legs also increase respiratory efficiency. Probably due the the larger muscle mass involved here.
3. Regarding altitude related illness...you gotta see a doc if you have concerns in this area. Headaches at altitude are usually treated with plenty of water...gotta stay hydrated...and aspirin and getting to camp as early as practical.
Being in better shape aerobically is a plus here as well.